If, with the use of, for example, a video tape recorder or a switcher as a transmission side peripheral device, it is attempted to transmit full-band high-vision (high definition TV or HDTV) digital signals (not compressed; 1.485 Gbps) from the transmission side peripheral device over a medium to long range distance to a receiving side peripheral device, such as a monitor device, there is known a method of converting parallel hi-vision signals supplied from the transmission side peripheral device via parallel digital interface into serial optical signals by an optical transmission device 51, transmitting the converted serial optical signals over an optical fiber 52 to the optical transmission device 51 to an optical receiving device 53, re-converting the transmitted signals by a parallel digital interface by the optical receiving device 53 and sending the resulting signals over the parallel digital interface to the receiving side peripheral device, as shown in FIG. 1.
There is also known a method of converting analog hi-vision signals, such as Y, Pb or Pr, sent from the transmitting side peripheral device over an analog interface, into optical signals by an optical transmission device 61, transmitting the optical signals over an optical fiber 62 to an optical receiving device 63, re-converting the transmitted optical signals into analog hi-vision signals by the optical receiving device 63 and sending the resulting signals to the receiving side peripheral device, as shown in FIG. 2.
Meanwhile, if parallel hi-vision signals are sent from the transmitting side peripheral device to the optical transmission device 51 via the parallel digital interface or from the optical receiving device 53 to a receiving side peripheral device via the parallel digital interface, as shown in FIG. 1, there is produced transmission delay unbalance between cables. If devices having parallel digital interface are separated a long distance from each other, synchronous detection by the receiving side becomes difficult. Moreover, a large number of transmission circuits are required.
If the transmitting side peripheral devices are connected to the optical transmission device 61 over an analog interface, as shown in FIG. 2, transmission delay unbalance is similarly produced between cables. Moreover, signal deterioration is severer than with digital signals thus necessarily imposing limitations on the distance between devices.
In both of the above methods, plural transmission paths (mediums) such as cables are required between the transmitting side peripheral device and the optical transmitting device, thus increasing the number of connection steps and the system size.
In addition, both methods suffer from an inconvenience in connection with extension of point-to-point connection due to system configurations.
In view of the foregoing, it is an object of the present invention to provide a digital signal transmission device in which sound quality deterioration to the receiving side peripheral device can be suppressed despite the fact that no complex structure is necessitated.
It is another object of the present invention to provide a digital signal transmission device in which plural transmission mediums are not needed for interconnection with the receiving side peripheral devices.